The present invention relates to pavement surfacing apparatus and more particularly to a mechanism for applying a layer of aggregate material such as crushed stone, sand, and tar chips to selected areas of an asphalt surface.
Pavement resurfacing, typically referred to as xe2x80x9cchip sealing,xe2x80x9d is a common practice in the art of roadway and parking lot maintenance. The process begins with repairing damaged areas such as cracks and pot holes, and then coating the roadway or parking lot with liquid asphalt to seal the paved surface. The attachment of aggregate materials to the coated surface completes the process. Attaching aggregate materials to liquid asphalt coated pavement surfaces has long been used to prevent problems such as slippage between planes of old and new pavement surfaces upon resurfacing, and the characteristic problem of sprayed asphalt having a low coefficient of friction. Chip sealing serves to key the asphaltic overlay to the pavement below to prevent the formation of a slippage plane. Chip sealing also eliminates slippery conditions that typically occur on roads, highways and parking lots at curves, traffic lights, and railroad crossings.
The aggregate material used in chip sealing is usually selected from hard, durable material such as crushed stone or sand, or tar chips which provide the extra advantage of efficiently resurfacing an asphalt surface with a product that can be recycled from the site. The aggregate particles are generally selected between xe2x85x9 to xe2x85x9c inch in size to provide a relatively compact packing of the aggregate on the asphalt surface. Larger aggregates and mixtures of different sizes of aggregate may be used to achieve different levels of compactness. This compact packing provides a surface smooth enough to provide a comfortable ride for vehicles traveling on the surface while at the same time providing small channels for water to escape so that hydroplaning and a loss of traction can be avoided by automobiles and pedestrians alike.
While chip sealing typically requires large equipment to cover large areas of pavement efficiently, this equipment cannot effectively resurface the edges, corners, and areas around immovable obstacles. These hard to reach areas must typically be resurfaced manually, or left free of an aggregate seal. However, a small mechanism similar to the large paving equipment used to spread aggregate over these areas could solve this problem to protect these hard to reach pavement surfaces.
Equipment used in pavement resurfacing is typically very large and expensive to operate. For example, a chip spreader vehicle that is commonly used in maintenance projects is a highly specialized automotive vehicle having a chip receiving bin on its back end, a chip dispensing hopper with a power driven auger therein on its front end, and a conveyor system for conveying the chips from the receiving bin to the dispensing hopper. A conventional dump truck is backed up so that its tail gate end is adjacent the chip receiving bin of the chip spreading vehicle, and its dump bed is raised to deliver the chips at a controllable delivery rate into the chip receiving bin. The dump truck is connected to the chip spreading vehicle and is towed by the vehicle as it is operated to accomplish its chip spreading task. This type of highly specialized vehicle is very expensive both from its initial cost and operating cost standpoints and its use is usually reserved for relatively large jobs.
Another commonly used chip spreader mechanism, typically referred to as a xe2x80x9ctailgate spreader,xe2x80x9d is mounted on the back of a dump truck to convert it into a special use machine.
In both of the above devices, the objective is to spread a layer of chips on large areas of the paved surface. But, the use of either one of these prior art machines cannot be economically justified for spot repair work, shoulder work, or work in hard to reach areas of paved surfaces. Thus, pavement resurfacing on the small scale is usually accomplished by first cleaning the surface and then repaving with an asphalt/aggregate mix, leveling it by hand, and finishing the repair by rolling it with a hand operated roller. Since no mechanized equipment for applying an asphalt seal coating and applying a chip coating is available for such small scale work, the chip seal coating is simply omitted. In the absence of such a coating, the repaired areas are subject to relatively rapid deterioration due to traffic and environmental damage. Therefore, a need exists for an efficient mechanism for applying a layer of aggregate to selected areas of a paved surface.
In accordance with the present invention, a new and useful mechanism is disclosed for applying a layer of aggregate material on selected areas of a paved surface that has been repaired and sealed with a spray coating of uncured liquid asphalt. The applicator mechanism includes an adjustable mounting bracket allowing the mechanism to operate with machines such as skid loaders, front loaders, and the like. A hopper is carried by the mounting bracket and is configured to provide an elongated aggregate dispensing slot on its lower end. A spreader shaft is mounted transversely to the intended movement path of the mechanism and attached by bearings to the inside surfaces of the hopper side walls. The spreader shaft contains a plurality of projections and is driven by a motor.
Working in combination with the spreader shaft are paddles in communication with one or more tension springs to control the size and amount of aggregate leaving the hopper. One end of the paddles surround a separate paddle shaft. A tension handle attached to one end of the paddle shaft allows the springs to be turned in a manner to increase or decrease the force applied to the paddles. The tension handle in turn works in combination with a toothed rack to hold the tension handle in one of several predetermined positions. Accordingly, an object of the present invention is to provide a new and useful mechanism for applying a layer of aggregate on selected areas of a paved surface.
Another object of the present invention is to provide a new and useful applicator mechanism of the above described character having a spreader shaft assembly for spreading the aggregate in a uniform layer.
Another object of the present invention is to provide a new and useful applicator mechanism of the above described character having a paddle shaft means to variably adjust the size and volume of aggregate deposition onto the spreader shaft and thus onto a paved surface.
Another object of the present invention is to provide a new and useful applicator mechanism of the above described character having a tension handle to variably adjust the tension applied to the paddles thereby controlling the thickness of the aggregate spread on a paved surface.
Yet another object of the present invention is to provide a new and useful applicator mechanism of the above described character having an adjustable mounting bracket to allow attachment to many different machines and allowing manipulation of the applicator mechanism to apply a layer of aggregate in an uncured coating of liquid asphalt previously applied on the selected area of the paved surface.
The foregoing and other object of the present invention, as well as the invention itself may be more fully understood from the following description when read in conjunction with the accompanying drawings.